Air conditioning systems are currently commonplace in homes, office buildings and a variety of vehicles including, for example, automobiles. Over time, the refrigerant included in these systems becomes depleted and/or contaminated. As such, in order to maintain the overall efficiency and efficacy of an air conditioning system, the refrigerant included therein may be periodically replaced or recharged.
Portable carts, also known as recover, recycle, recharge (“RRR”) refrigerant service carts or air conditioning service (“ACS”) systems, are used in connection with servicing refrigeration circuits, such as the air conditioning unit of a vehicle. The portable machines include hoses coupled to the refrigeration circuit to be serviced. A vacuum pump, compressor, and a series of valves operate to recover refrigerant from the vehicle's air conditioning unit, flush the refrigerant, and subsequently recharge the system from a supply of either recovered refrigerant and/or new refrigerant from a refrigerant tank.
Each ACS unit includes many tube and/or hose assemblies which interconnect a manifold block and various other components. A vast majority of the tube and hose assemblies are connected to the manifold block and various other components with some variation of a female nut and a mating male fitting. Installation of each connection often requires an open-face wrench to tighten the female nut until a requisite torque specification is achieved. Although the female nut and mating male fitting often yield sufficient performance in the presence of the high pressure fluids in the system, the time required to assemble the female nut and mating male fitting results in increased manufacturing and maintenance time. In some instances, the assembly time of each tube or hose end has been is estimated to be in excess of fifteen seconds, which, when summed among all the fittings in the ACS unit, contributes to manufacturing time and labor cost.
Certain “quick-connect” fittings are utilized in the pneumatic field to reduce the time required to connect various tubes and hoses. One such fitting 10 is depicted in FIG. 1, and includes a body 12 having external threads 14 for connection to a manifold (not shown) or some other receiving structure, and defines an internal passage 16. A collet 18 is positioned within one end of the body 12 in the passage 16, and includes teeth 20 configured to engage the outer surface of a tube or hose (not shown). A sealing O-ring 22 is positioned in the passage 16 of the body 12, and is separated from the collet 18 by a plastic back ring 24.
In order to connect a tube or hose (not shown) with the fitting 10, the tube or hose is inserted through an end opening 26, which is defined in the collet 18, until the tube or hose protrudes far enough into the passage 16 that the end of the tube or hose contacts a step 28 of the body 12. The plastic back ring 24 engages an outer surface of the teeth 20 of the collet 18 to maintain the teeth 20 in pressing engagement with the outer surface of the tube or hose, thereby providing a holding force sufficient to hold the tube in place.
If the tube or hose is pulled, the back ring 24 cooperates with the outer surface of the teeth 20 to press the teeth inward, thereby providing an increase in the holding force sufficient to prevent the tube or hose from being pulled out of the passage 16. In order to remove tube or hose, the collet 18 is pressed until an end face 30 of the collet 18 contacts an end face 32 of the body 12. Pressing the collet 18 moves the teeth to a position in which the outer surface of the teeth 20 can no longer engage the plastic back ring 24, allowing the tube or hose to be freely pulled out of the passage 16 without the teeth pressing inward on the tube or hose.
Although previous quick-connect fittings, such as the fitting 10, provide for connecting and removal of the tube or hose in a timely manner, the fittings are not intended for high-pressure applications such as those encountered in ACS units. Previous quick-connect fittings are rated for pressures well under 1000 psi, while ACS units often require fittings capable of withstanding pressures in excess of 2500 psi.
In high-pressure applications, for example, the quick-connect fitting 10 fails due to the high-pressure on the back end of the O-ring 22 forcing the O-ring 22 to press against the teeth 20 of the collet 18. By pressing against the teeth 20 of the collet 18, the O-ring 22 may tear, causing leaks, or the collet 18 may buckle, causing the tube to release violently from the fitting. Moreover, since the plastic back-ring 24 is not fluid-tight and is not capable of withstanding the high-pressures of an ACS unit, the mere presence of the back ring 24 does not eliminate the problems of the prior art quick-connect fitting 10.
A connection system for connecting tube and hose assemblies that withstands high-pressure performance requirements and reduces assembly time is therefore desirable.